Figure 9.

New Models for Plant Archesporial Initiation in the Ovule and Anther.

Cells colored in red, blue, yellow, magenta, orange, and green indicate archesporial cells, SCs, primary parietal cells, tapetal cells, middle layer cells, and endothecium cells, respectively. Excess female archespores are generated in the ovule, and one of the archespores only develops in an SC, probably by means of SPL-like gene function to promote SC generation and MSP1 function to repress support cells of SCs developing into SCs; no rice ortholog of the SPL gene has been identified yet. Analogous with ovule development, male archespores might also be generated in excess of SCs, and SPL and MSP1 might determine the fate of SCs and parietal cells in microsporangia.